Objective:To find the methods of differential diagnosis between keloid and hypertrophic scar.Method:The morphological characters of keloid and hypertrophic scar were compared under light microscope and electron microscope.Immunohistochemistry method was used to detect the expression of Bcl-2 protein in fibroblast of both lesions.Results:Both keloid and hypertrophic scar showed lots of fibroblast,microvessels and collagen fibers.The ultrastructures of both lesions were found that most fibroblasts were of active celltypes,they contained abundant coarse endoplasmic reticulum,prominent Gogi complexes,and the fibrils in the lesions were irregularly arranged.Meanwhile,the expression of Bcl-2 protein in keloid was significantly higher than that in hypertrophic scar ( P 0 005).Conclusion:The morphological characters of keloid were hardly to be differentialted from hypertrophic scar,but the immunochemical differences of Bcl-2 protein might be useful in the differential diagnosis between keloid and hypertrophic scar.